Researches for higher electrical conductivity copper-based materials

Copper and copper-based materials are widely used in power electronics,auto-mobiles,mechanical manufacturing and high-tech manufacturing fields such as aerospace,telecommunications and integrated circuits owing to their compre-hensive advantages in mechanical,electrical conductivity and processing prop-erties.With the rapid development of technology,many emerging technical fields have introduced more challenging requirements for the electrical conductivity of copper.This article reviews the research status of high-conductivity copper-based materials and introduces three methods to improve electrical conductivity,including purification,alloying and addition of nanocarbon materials.We sum-marise the advantages,disadvantages and future development trends of methods for improving copper conductivity.The key to producing high-conductivity copper-based materials is development of low-cost,continuous and stable processes.

Numerical Model Research on Rotational Performance of Beam-Column High-Strength Bolt Extension End-Plate Connection Node

The high-strength bolted end plate connection is widely used in the construction industry with its green environmental protection and excellent seismic performance. The joints of the joints are semi-rigid, the force performance is extremely complicated, and the experimental research cost is relatively high, and the cycle is very long. Therefore, the establishment of an efficient numerical model is of great significance for evaluating the force performance of high-strength bolt end plates. In this paper, the influence of different material models on the rotation performance of the joint is studied by numerical simulation, and the bending moment-rotation curve is obtained. The numerical simulation and the experimental results are in good agreement, so as to provide a reference for the design and application of this kind of joint.

High-strength hydrogels:Fabrication,reinforcement mechanisms,and applications

With the continuous appearance and expansion of high-strength hydrogels in emerging fields such as industry,medicine,and green development,the synthesis and application of high-strength hydrogels have developed dramatically and achieved remarkable results from the aspects of raw materials,preparation methods,and reinforcement mechanisms.However,there is still a lack of systematic reviews on high-strength hydrogels.Herein,we first discuss the advantages of natural and synthetic materials,and the characteristics of high-strength hydrogels prepared from different raw materials;we then expound on the influence mechanism of physical interactions or chemical bonds on the strength of the hydrogel from three aspects:physical cross-linking,chemical cross-linking,and dynamic chemical cross-linking;at last,we systematically expound the strengthening strategies,including double network/multi-network,nanocomposite,topology,supramolecular polymerization,and characteristics and strengthening mechanisms of such high-strength hydrogels.In addition,based on the development status of high-strength hydrogels,we combined the application requirements and the existing drawbacks of high-strength hydrogels to propose their possible development directions in the future.

Polymeric Complex Nanoparticles Enable the Fabrication of Mechanically Superstrong and Recyclable Poly(aryl ether sulfone)-based Polymer Composites

It is a long-term pursuit,and also,a challenge to significantly improve the mechanical strength of thermoplastic polymers using readily dispersed polymers as nanofillers.In this study,we demonstrated that in situ formed carboxylic acid-functionalized poly(aryl ether sulfone)(PAES-COOH)/polyvinylpyrrolidone(PVPON)complex nanoparticles can significantly enhance the mechanical strength of PAES-COOH by mixing PAES-COOH with a small fraction of PVPON.The PAES-COOH/PVPON10%composite,which contained∼10 wt%PVPON,exhibited a tensile strength of∼104.8 MPa and Young’s modulus of∼932.2 MPa,which were∼2.0 and∼1.7 times higher than those of the PAES-COOH,respectively.The PAES-COOH/PVPON nanoparticles which were uniformly dispersed in PAES-COOH matrices and had strong hydrogen-bonding interactions with PAES-COOH,served as nanofillers to reinforce the mechanical strength of the PAES-COOH.The PAES-COOH/PVPON_(10%)composites possessed excellent solvent-assisted healability,and the fractured composites could be healed to restore their original mechanical strength.Meanwhile,the PAES-COOH/PVPON_(10%)composites could be recycled multiple times,and yet retained their shape integration and their original mechanical strength.